[The venereal morbidity in Russia in 1914-1924].

It is accepted to explain increasing of venereal diseases during years of the Revolution by degradation of morality and general disorder of system of state administration and sanitary services in Russia. The cross-verification of information presented in scientific publications and primary information sources makes it possible to look into following issues: degree of venereal (syphilitic) contamination of population of pre-revolutionary Russia; influence on sanitary statistics by erroneous diagnostics and convictions of Zemstvo medicine about predominantly non-sexual path of transmission of syphilis pathogen in Russian countryside; dynamics and sources of venereal morbidity in wartime. The high indicators of pre-revolutionary statistics of venereal infections could be affected by diagnostic errors.

[Non-mellow season of domestic health resort business in 1914-1922].

For a long time, balneotherapy and health resort treatment was considered the privilege of the well-to-do. In Russia, recreational areas developed much later than in Europe. Their development was directly related to restoring the health of the military, the more so since these areas, with few exceptions, were located near the outskirts of the country and the location of large military contingents.

Local and global dynamics in collective movements of embryonic cells.

Several important morphogenetic processes belong to the category of collective cell movements (CCM), by which we mean coordinated rearrangements of many neighboring cells. The causes of the dynamic order established during CCM are still unclear. We performed statistical studies of rates and angular orientations of cell rearrangements in two kinds of embryonic tissues, which we categorized as "committed" (in the sense of being capable of autonomous CCM) as opposed to "naïve" tissues, which are those that require external forces in order to exhibit full scale CCM.

Active reinforcement of externally imposed folding in amphibians embryonic tissues.

Although the folding of epithelial layers is one of the most common morphogenetic events, the underlying mechanisms of this process are still poorly understood. We aimed to determine whether an artificial bending of an embryonic cell sheet, which normally remains flat, is reinforced and stabilized by intrinsic cell transformations. We observed both reinforcement and stabilization in double explants of blastocoel roof tissue from Xenopus early gastrula embryos.

[Statistical study of rapid mechanodependent cell movements in deformed explants of African clawed frog Xenopus laevis embryonic tissues].

Computer analysis of artificially deformed (stretched or compressed) double explants (sandwiches) of the blastocoel roof (BRs) and suprablastoporal region (SBRs) of African clawed frog Xenopus laevis early gastrula has been performed using frames of time-lapse microfilming. During the first 14 min after cutting off, the velocities and displacement angles of several hundreds of cells relative to one another, as well as to fixed points and the extension axis, were measured in the control and deformed samples. It has been found that the deformation of samples leads to a rapid reorientation of large cell masses and increase in the velocities of movements along the extension axes or perpendicularly to the compression axes.

Neuro-mesodermal patterns in artificially deformed embryonic explants: a role for mechano-geometry in tissue differentiation.

The mutual arrangement of neural and mesodermal rudiments in artificially bent double explants of Xenopus laevis suprablastoporal areas was compared with that of intact explants. While some of the bent explants straightened or became spherical, most retained and actively reinforced the imposed curvature, creating folds on their concave sides and expanding convex surfaces. In the intact explants, the arrangement of neural and mesodermal rudiments exhibited a distinct antero-posterior polarity, with some variability.

[Mechanodependent cell movements in the axial rudiments of Xenopus gastrulae].

Sandwich explants of the suprablastoporal area of Xenopus early-mid gastrula and same stages of entire embryos were stretched with two needles perpendicular to the direction of natural elongation of the axial rudiments. The changes in the embryonic shape and histological structure were monitored as well as the arrangement of descendants of one of dorsal blastomers labeled with fluorescein-dextran at the 16-cell stage. A substantial fraction of stretched explants reoriented along the applied stretch direction.

[Mechanical feedback in morphogenesis and cell differentiation].

The review is concerned with studies of mechanical stresses and mechanical feedbacks on the cellular level. The dependence of responses of cells and embryonic tissues on mechanical stresses and their ability to generate these stresses by themselves have been shown. Regular feedbacks between external (passive) and internal (active) mechanical stresses have been established that are required for the viability of cells, determine the direction of their differentiation, and provide the self-organization of morphogenetic processes.